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Infectious Disease > Week 5: Parasitology Part II > Flashcards

Week 5: Parasitology Part II Flashcards

1
Q

learning objectives

A

For the parasitic organisms identify

  • the geographical region of risk
  • mode of transmission
  • Life-cycle
  • clinical symptoms
  • clinical complications of infection
  • laboratory diagnostic tests
  • appropriate treatment
  • side effects of treatment
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2
Q

Case 1

A
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3
Q

Question

A

D. Schistosoma japonicum

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4
Q

Schistosomiasis Life-cycle

A
  • Infected person (Reservoir) releases trematode eggs in urine or stool
  • Eggs contaminate freshwater
  • Eggs hatch and infect snails (intermediate host) and divide
  • Free swimming cercariae released into the water and penetrate human skin

People defecate oocytes which enter freshwater and eggs hatch and infect snails and divide, the snails release free-swimming cercariae into the water which penetrate human skin

Cercariae lose tails during penetration and become schistosomulae and enter the circulation and migrate to the portal blood in liver and mature into adult worms that perform sexual reproduction

Paired adult worms migrate to mesenteric venules of bowel/rectum laying eggs that circulate to the liver and are shed in stools to infect more snails

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5
Q

Schistosomiasis pathophysiology

A

eggs can migrate to the liver to be shed in stools or to other tissues such as wall of intestine or liver (mansoni or japonicum), bladder wall (haematobium) -> granulomas -> fibrosis

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6
Q

Liver Schistosomiasis

A
  • Schistosoma mansoni
  • Schistosoma japonicum
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7
Q

Bladder wall fibrosis Schistosomiasis

A

Schistosoma haematobium

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8
Q

Clinical manifestations of Schistosomiasis

A
  • Swimmer’s itch: Cercariae penetrating skin (pruritic papular rash after penetration)
  • Katayama fever (Acute schistosomiasis)
    • systemic hypersensitivity reaction to Schistosoma antigens occurring 1-2 months post-exposure
    • Fever, chills, cough, urticaria, angioedema, arthralgias, dry cough, abdominal pain, lymphadenopathy, and splenomegaly
    • Massive eosinophilia
  • Deposited eggs cause granulomas & fibrosis
    • periportal fibrosis/portal hypertension
    • Hematuria and bladder cancer
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9
Q

Would you predict that a patient with Schistosomiasis would have eosinophilia?

A

Yes, during swimmer’s itch phase and especially during the Katayama fever.

The granulomatous stage doesn’t have a big immune response

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10
Q

What laboratory test to diagnose Schistosomiasis

A
  • Stool test if it is in the liver and biliary system
  • Urine for bladder
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11
Q

Schistosoma species

A
  • Schistosoma mansoni
  • Schistosoma haematobium
  • Schistosoma japonicum
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12
Q

Schistosoma mansoni region

A
  • Africa
  • South America
  • Carribean
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13
Q

Schistosoma mansoni eggs found in

A
  • Stool
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14
Q

Schistosoma haematobium region

A
  • Africa
  • Middle East
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15
Q

Schistosoma haematobium eggs found in

A

Urine

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16
Q

Schistosoma micro egg exam

A
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17
Q

Schistosoma mansoni micro egg exam

A
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18
Q

Schistosoma japonicum region

A
  • Indonesia
  • China
  • SE Asia
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19
Q

Schistosoma japonicum eggs found in

A

Stool

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20
Q

Schistosoma japonicum micro exam of eggs

A
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21
Q

Schistosomiasis treatment

A

Praziquantel

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22
Q

Praziquantel MOA

A

Kills adult schistosomes and causes them to become dislodged from mesenteric, hepatic or pelvic veins -> phagocytosed in liver

Kills adult worms (does not kill eggs or treat fibrosis)

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23
Q
A
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24
Q

Praziquantel best used when?

A

During acute schistosomiasis (single dose 6-8 weeks after last exposure to potentially contaminated freshwater)

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25
Q

Praziquantel side effects

A

Majority of side effects develop due to host immune reaction to killed parasites (release lots of antigens when they die)

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26
Q

Examples of Trematode infections

A
  • Schistosomiasis
  • Paragonimus westernmani
  • Clonorchis sinensis
  • Fasciola hepatica
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27
Q

Paragonimus westernmani region

A

SE Asia

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28
Q

Paragonimus westernmani AKA

A

Lung fluke

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29
Q

Paragonimus westernmani transmission

A

ingestion of undercooked crabs/crayfish contaminated with metacercariae

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30
Q

Signs & symptoms of Paragonimus westernmani

A
  • Lung cyst rupture
  • Chronic bronchitis
  • TB-like picture
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31
Q

Paragonimus westernmani diagnosis

A
  • eggs in sputum
  • serology
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32
Q

Paragonimus westernmani Tx

A

Praziquantel

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33
Q

Clonorchis sinensis region

A

Asia

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34
Q

Clonorchis sinensis AKA

A

Liver fluke

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35
Q

Clonorchis sinensis transmission

A

ingestion of undercooked freshwater fish contaminated with metacercariae

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36
Q

Signs & Symptoms of Clonorchis sinensis

A
  • obstructive jaundice
  • biliary strictures
  • pigmented gallstones
  • cholangitis
  • cholangiocarcinoma
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37
Q

Clonorchis sinensis Dx

A

Eggs in stool

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38
Q

Clonorchis sinensis Tx

A

Praziquantel

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39
Q

Would becoming a vegetarian eliminate the risk of intestinal parasite infection?

A

No, for example Fasciola hepatica

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40
Q

Biliary strictures & cholagniocarcinoma and Hx of undercooked fish

A

Clonorchis sinensis

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41
Q

Undercooked crab/crayfish

A

Clonorchis westernmani

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42
Q

Fasciola hepatica region

A

Worldwide trematode

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43
Q

Fasciola hepatica AKA

A

Common Liver Fluke

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44
Q

Common Liver Fluke

A

Fasciola hepatica

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45
Q

Fasciola hepatica definitive host

A

Sheep/cattle

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46
Q

Fasciola hepatica intermediate host

A

Snail

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47
Q

Fasciola hepatica Incidental host

A

Human

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48
Q

Fasciola hepatica transmission

A

ingestion of raw watercress or other plants contaminated with metacercariae -> migrate through duodenal wall -> peritoneum -> liver -> biliary ducts -> obstruction

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49
Q

Fasciola hepatica Dx

A

Eggs in stool or duodenal or biliary aspirated

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50
Q

Fasciola hepatica Tx

A

Triclabendazole

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51
Q

Triclabendazole caveat

A

Not FDA approved so must obtain from CDC

52
Q

Case 2

A
53
Q

Question

A

C. Taenia solium

54
Q

Taenia solium type

A

Helminth: Cestode/tapeworm

55
Q

Taenia solium Intermediate host

A

pig

56
Q

Taenia solium definitive host

A

human

57
Q

Taenia solium transmission

A
  • Human ingestion of larval cyst in undercooked pork causes Taeniasis (intestinal infection) with adult worms -> excrete eggs in stool
  • Human ingestion of eggs from fecal-contaminated water or vegetation causes Cysticercosis (tissue infection)
58
Q

Human ingestion of larval cyst of Taenia solium

A

Taeniasis (tape-worm intestinal infection)

59
Q

Human ingestion of larval cyst of Taenia solium

A

Cysticercosis (tissue infection)

60
Q

Describe the life cycle of Taenia solium

A
  • pigs ingest fecal-contaminated feed
  • oncospheres hatch and penetrate pig intestinal wall and circulate to the musculature
  • Oncospheres develop into cysticerci in pig muscle
  • Humans infected by ingesting undercooked or raw infected meat
  • Taeniasis: Scolex attaches to intestines and grows to adults in small intestine
  • Cysticercosis: oncospheres hatch penetrate the intestinal wall and circulate to musculature, cysticerci may develop in any organ being more common in subcutaneous tissues as well as in the brain and eyes
61
Q

Tenia solium Dx

A
  • Imaging
  • serology
62
Q

Tenia solium Tx

A

Praziquantel x 1 (cysticidal)

Albendazole (cysticercosis)

or may not need treatment

63
Q

Diphyllobathrium latum AKA

A

Fish tapeworm

64
Q

Diphyllobathrium latum transmission

A

Ingestion of undercooked freshwater fish

65
Q

Diphyllobathrium latum signs & symptoms

A

competes for vit B12 in host intestine -> macrocytic anemia

66
Q

Diphyllobathrium latum Dx

A

eggs in stool

67
Q

Diphyllobathrium latum Tx

A

Praziquantel

68
Q

An infection with which cestode can lead to hydatid cyst in the liver or lung?

A

Echinococcus

69
Q

How does a patient become infected with Echinococcus?

A
70
Q

How is Echinococcus Dx’ed?

A
  • Imaging to see hydatid cyst
  • Serologies
  • Never aspirate hydatid cyst because can cause anaphylactic shock
71
Q

Who commonly gets Echinococcus?

A

Raw food or food infected with dog feces (Sheep herders commonly get Echinococcus)

72
Q

Case 3

A
73
Q

Do you aspirate hydatid cyst?

A

No, can cause anaphylactic shock

74
Q

Question

A

C. Stool Ova & Parasite

75
Q

Case 3 Stool sample

A

Strongyloidiasis

76
Q

Question

A

C. Strongyloides stercoralis

77
Q

Strongyloides stercoralis stool and blood agar

A
78
Q

Describe the life-cycle of Strongyloides stercoralis

A
  • Rhabdiform larvae in the intesine are excreted in stool and
  • autoinfect
  • but also develop into free-living adult worms that perform sexual reproduction
  • eggs are produced by fertilized female worms
  • Rhabditiform larvae hatch from embryonated eggs
  • The rhabditiform larvae develop into infective filariform
  • Infective filariform larvae penetrate the intact skin initiating the infection
  • The filariform larvae enter the circulatory system and are transported to the lungs and penetrate the alveolar spaces, they are carried to the trachea and pharynx, swallowed and reach the small intestine where they become adults
  • Autoinfection rhabditiform larvae in large intestine become filariform larvae, penetrate intestinal mucosa or perianal skin and follow the normal infective cycle
  • Eggs deposited in the intestinal mucosa hatch and migrate to the lumen
  • Rhabditiform larvae in the intestine are excreted in stool
79
Q

Describe the initial infection of Strongyloidiasis

A

Filariform larvae penetrate the skin -> migrate through tissue into blood -> to lungs -> into alveoli -> trachea -> cough up and swallow -> in intestine -> can cross intestine wall (perforation) to peritoneum

80
Q

Strongyloidiasis signs & symptoms of initial infection

A

Skin

  • Intense pruritis at site of skin penetration

Lungs

  • Transient fever, cough and wheezing

GI

  • symptoms only if lots of worms
  • abdominal pain, vomiting, diarrhea
  • Perforation with peritonitis from GI flora
81
Q

Strongyloidiasis signs & symptoms of autoinfection

A
  • Larva currens: peri-anal serpiginous urticarial rash
  • can lead to chronic infection for decades
  • Hyperinfection syndrome: Autoinfection in immunocompromised patients, Abdominal pain, diffuse pulmonary infiltrates, septicemia or meningitis with GNR
82
Q

Describe autoinfection of Strongyloidiasis

A

female worm lays eggs in human bowel wall -> larva hatch -> larval invasion of perianal skin

83
Q

Strongyloidiasis stercoralis Dx

A

Stool & blood agar

In the stool: Rhabditiform larvae in stool, sputum, CSF, other body fluid

Stool culture shows GNR along the track of movement of larvae

84
Q

Strongyloidiasis Tx

A
  • Ivermectin x 1
  • Second line: Albendazole x 7 days
85
Q

Ascaris lumbricoides type

A

Nematode/round-worm

86
Q

Ascaris lumbricoides transmission

A

Fecal-oral

87
Q

Ascaris lumbricoides infection type

A

Intestinal infection

88
Q

Ascaris lumbricoides Dx

A

Eggs in stool

89
Q

Ascaris lumbricoides Tx

A
  • Albendazole
  • Mebendazole
90
Q

Ascaris lumbricoides overview

A
91
Q

Describe the life-cycle of Ascaris lumbricoides

A
  • Ingestion of eggs in fecal-contaminated food
  • egg releases larval worm which penetrates duodenum
  • Carried in bloodstream to pulmonary circulation
  • Larvae break free in alveoli where they mature over 3 weeks
  • Coughed up and swallowed
  • Adults mature in intestine & copulate and release eggs in stool
92
Q

Necator americans region

A

New world

93
Q

Ancylostoma duodenale region

A

Old world

94
Q

Necator americans description

A

Roundworm “hookworm”

95
Q

Necator americans distribution

A

Tropics, subtropics

96
Q

Necator americans Transmission

A

Contaminated soil -> larvae penetrate through skin

97
Q

Necator americans definitive host

A

humans

98
Q

Necator americans clinical syndrome

A
  • cutaneous larva migrans & eosinophilia: Pruritic maculopapular rash at site of penetration
  • Nausea, vomiting, diarrhea, abdominal pain
  • Anemia: sucks blood from intestinal wall
99
Q

Necator americans Dx

A

Detection of eggs in stool

100
Q

Necator americans Tx

A

Albendazole

101
Q

Describe the life cycle of Necator americans

A
  • eggs in feces, rhabditiform larva hatches
  • larva in fecal-contaminated soil in the tropics/subtropics become filariform larva
  • filariform larva penetrate the skin from walking barefoot and migrates through blood vessels to lungs
  • larva penetrate alveoli and ascend to pharynx and are swallowed (transient pulmonary symptoms)
  • become adult worms in intestines and perform sexual reproduction and cause anemia in host
  • Are released in feces
102
Q

Necator americanus analogous in old world

A

Ancylostoma duodenale

103
Q

Trichuris trichuria type

A

Nematode

104
Q

Trichuris trichuria exposure

A

soil containing eggs

105
Q

Trichuris trichuria clinical syndrome

A

whipworm: tenesmus, rectal prolapse

106
Q

Trichinella type

A

Nematode

107
Q

Trichinella exposure

A

Ingesting contaminated food (pig, bear)

108
Q

Trichinella clinical syndrome

A
  • mild diarrhea
  • periorbital edema
  • myalgias
109
Q

Dracunculus mediensis description

A

nematode

110
Q

Dracunculus mediensis exposure

A

ingestion of contaminated water

111
Q

Dracunculus mediensis clinical syndrome

A

Guinea worm: malaise, fever, adult worm emerges

112
Q

Dracunculus mediensis type

A

Nematode

113
Q

Enterobius vermicularis type

A

nematode

114
Q

Enterobius vermicularis exposure

A

Fecal-oral

115
Q

Enterobius vermicularis clinical syndrome

A
  • intestinal pinworm
  • anal pruritis
116
Q

Loa Loa type

A

Nematode

117
Q

Loa Loa exposure

A
  • Deer fly
  • Horse fly
118
Q

Loa Loa Clinical syndrome

A
  • Conjunctival worm
119
Q

Onchocerca volvulus type

A

Nematode

120
Q

Onchocerca volvulus exposure

A

Female blackfly bite

121
Q

Onchocerca volvulus clinical syndrome

A

River blindness

122
Q

Toxocara canis type

A

nematode

123
Q

Toxocara canis exposure

A

fecal-oral

124
Q

Toxocara canis clinical syndrome

A

visceral larva migrans

125
Q

Wuchereria bancrofti type

A

nematode

126
Q

Wuchereria bancrofti exposure

A

female mosquito

127
Q

Wuchereria bancrofti clinical syndrome

A

Elephantiasis (lymphatic filariasis)

Infectious Disease (82 decks)

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